Field of the Invention
The present invention relates to a vibration wave motor, and particularly, relates to a vibration wave motor for linear, in which an elastic body is formed into a plate shape.
Description of the Related Art
Conventionally, vibration wave motors, which have features such as compact lightweight, high-speed drive and silent drive, have been employed for a lens barrel of an imaging device. Among them, with regard to a vibration wave motor for linear drive, a vibration wave motor as below is disclosed in Japanese Patent Application Laid-Open No. 2014-183724. The vibration wave motor disclosed in Japanese Patent Application Laid-Open No. 2014-183724 as below is constituted by a vibration plate including protruding portions and performing high frequency vibration and a friction member in contact with the protruding portions. The vibrator that is caused to generate the high frequency vibration is brought into pressed contact with the friction member to move relatively the vibrator and the friction member. To reduce sliding loads generated by pressing force applied to the vibrator upon relative movement, a movable member that holds the vibrator and a fixing member that holding the friction member are configured to be capable of moving relatively in a freely sliding manner by rotating members.
In the vibration wave motor disclosed in Japanese Patent Application Laid-Open No. 2014-183724, the rotating members are disposed between the fixing member and the movable member thereby reducing sliding resistance upon relative movement. In this case, the rotating members are displaced between a recessed portion provided on the fixing member and a recessed portion provided on the movable member, and are urged against the fixing member through the movable member by the pressing force generated by the pressing member. In such the configuration, when impact or the like is applied to an ultrasonic motor and the applied impact force exceeds the aforementioned urging force, there has been a problem that the rotating members fall off of the recessed portions to cause drive to be unstabilized, further sliding loads to be increased or the like.